Age Changes in Renal Function 



237 



average of 20 subjects in each age group, are shown in Fig. 9. 

 From the three curves at the bottom of the chart it is clear that 

 although the usual age difference in glomerular filtration rate 

 was present, there was no significant effect of the pyrogen in 



40 



80 



120 

 MINUTES 



160 



200 



Fig. 9. Changes in glomerular filtration rate (Cin), 

 effective renal plasma flow (Cpah)j and filtration 

 fraction during the pyrogen reaction. Fifty million 

 killed typhoid organisms were injected intravenously 



at time. O O mean values for 14 subjects 



aged 70-85 years (O group). A A niean 



values for 20 subjects aged 50-69 years (M group). 



% mean values for 20 subjects aged 20-49 



years (Y group). 



(From: McDonald, Solomon and Shock, 1951). 



either the young, middle, or old subjects. The three curves in 

 the centre of the graph show clearly that, beginning about 80 

 minutes after the administration of the pyrogen, there was a 

 slow continuous rise in renal plasma flow in all groups of sub- 

 jects. Although the mean absolute increases were greater for 

 the young than for the old group, where increments were 



